/Engine/Source/Runtime/Engine/Public/GeomTools.h
Merge additive and subtractive polygons, split them up into additive polygons Assumes all polygons and overlapping polygons are valid, and the windings match the setting on the polygon
static [TArray](API\Runtime\Core\Containers\TArray)< [TArray](API\Runtime\Core\Containers\TArray)< FVector2D > > ReducePolygons ( const [TArray](API\Runtime\Core\Containers\TArray)< [TArray](API\Runtime\Core\Containers\TArray)< FVector2D >> & Polygons, const [TArray](API\Runtime\Core\Containers\TArray)< bool > & PolygonNegativeWinding )